A new radiological technique has been developed for high precision bone measurement with potential application to metabolic and metostatic bone disease. Transmission measurements are made over areas, such as the femoral neck, using a filtered, collimated beam from an X-ray tube. A series of moving slits is used to minimize the effects of scattered radiation. An image intensifier - TV system is used for radiation measurement. This allows high resolution area measurements with a small exposure (50 mrad). In the first project year the technique, and existing equipment, will be optimized. Accuracy and precision measurements will be done on bone specimens. During the second project year patients will be measured 3 times (0,4 and 8 months) to assess precision. Comparisons will be made to dual-photon (153-Gd) absorptiometry measurements (femoral neck, lumbar spine) and single-photon (125-I) absorptiometry measurements at the same locations. The method also will be used to examine bone tumors.